1. Field of the Invention
The present invention relates to a cleaning device for a plasma etching system for plasma etching a sample such as a semiconductor substrate.
2. Description of the Prior Art
In a conventional parallel plate electrode type plasma etching apparatus as shown in FIG. 1, a chamber (1) contains an upper electrode (2) facing to a lower electrode (3) having a sample table equipped with a water cooling pipe (4) and the chamber (1) is evacuated in a vacuum of about 10.sup.-4 to 10.sup.-5 Torr. Then, an etching gas such as CF.sub.4 +O.sub.2 is fed through an inlet (5) to maintain to a predetermined pressure and a high frequency electric power is fed from a power source (6) between the electrodes (2), (3) to form a plasma gas whereby a surface of a sample (7) such as a semiconductor substrate placed on the lower electrode (3) is etched. In the conventional plasma etching apparatus, a reaction product formed by the etching is adhered to an inner wall of the chamber (1). If the etching is repeated under such condition, the evacuation effect is reduced by the adhered reaction product to deteriorate the reproducibility and the sample (7) is disadvantageously stained by the reaction product.